It is believed that reducing dependence on fossil resources is one of the most effective solutions as a measure against the problem of global warming. Beginning with the use of biomass fuel, the active use of plant derived materials is believed to be an effective means for controlling the emission of CO2. In such a trend, the use of plant derived plastic is a very important key technology in helping to reduce dependence on fossil resources. Conventionally, polylactic acid (PLLA) has been a representative example of plant derived plastics, however, today products derived from plants are beginning to be produced using nylon and polyethylene (PE) which is a general purpose plastics and the use of petroleum derived PE of is gradually being replaced.
In the case where PE materials are used to achieve better mechanical properties, it is necessary to use high-density PE (HDPE) instead of low density PE (LDPE). However, even in PE derived from petroleum, it is not possible to simply replace LDPE with HDPE to achieve a less noticeable performance improvement. Since the elastic modulus of PE is low, an increase in performance is expected by blending with high modulus plastic such as PLLA in order to achieve high elastic modulus. However, in a convention mixing process, since there is no technique for a blend which mixes the PLLA and HDPE microscopically, modification of HDPE and the like did not progress. This situation is the same today where it is possible to use plant derived PE. See Japanese Laid Open Patent No. 2008-038142.